Manufacture of useful products from cellulose derivatives



Patented Dec. 26, 1933 MANUFACTURE oF- USEFUL PRODUCTS FROM CELLULOSE DERIVATIVES .Henry Dreyfus, London, England No Drawing. Application October18, 1929, Serial No. 400,745, and in Great Britain 0ctober29,

10 Claims. (01; 18-54) This invention relates in particular to the manufacture of filaments, yarns, threads, ribbons of filaments, threads or-yarns of or containing cellulose acetate, especially acetone-soluble cellulose acetate. T

The invention is particularly applicable to the production of'filaments, threads, or yarns of low filament denier, from cellulose acetate by evapo rative or dry spinning. In the so-called dry spinning or evaporative spinning'of filaments, threads or yarns from cellulose acetate solutions, as is known, the solution of cellulose acetate in a solvent or solvent mixture is spun through nozzles or spinnerets into a current or atmosphere of air or other gas, usually oi -elevated temperature, in 'spinnin'g cells or chambers, the solvent being thereby evaporated .to solidify'the filamerits. 1 V 7 Thesolven't commonly employed in the spinning solutions is acetone containing a small proportion of water'but other volatile solvents or solvent mixtures have also been employed.

The discovery has been made that in proportion as one uses increased quantities of water relatively to the solvent, in such spinning solu@ tions, theviscosity of the solution decreases to a lowest figure and then again' usually rises with further increase of the amount of. water. The curve of viscosity variation of the solutions with the varying amountsjof water employed therein, and the pointoi-lowest viscosityattained in the curve are subject to variation according, toothe characteristics of the cellulose acetate, and, for

any given temperature, according to the particu- ;lar solvent or solvents employed in the solution and the concentration 'of' the solution. It has been found for instance with acetone-soluble'cek lulose v acetate of a character largely employed for spinning yarns, that the viscosity of spinning solutions oi for example about 25% concentration prepared by dissolvingthe acetate in acetone of 'progressively greater dilution, starting from practically dry acetone, progressively decreases in proportion as the solutions contain more and" more water relatively to the acetone,

andattains a lowest degree of viscosity at 10-12% of water relatively to -88% of acetone after which the viscosity'again shows a rise with further increasesof-water and that the viscosity of the solutions can .be reduced'to one half or one third that of the solution in acetone containing very little or no water, by adding relatively substantial quantities'of water thereto. The above instance of course is only an illustrative example and in no way limitative, since, as before'indicated, the curve drawn to show the relation between the viscosities of thesolution and the varying amounts of water" employed therein is subject to variation according to a I number of. factors. 'It maybe mentioned for instance that the point, of water dilution of acetone at. which the lowest degree of viscosity is attained for a given cellulose 'acetate'varies with the degreexor'stage to whichlthegiven celluloseacetate has been ripened, and in the case of an acetate'zwhichx has been ripenedto astage'ol' solubility in acetone diluted with considerable quantities of watenthe; lowest viscosity oisolutions 'ofrcellulose acetate in acetone containing more than 5 percent. of water,,especially those. containing relatively substantial proportions of vwater, can be readily drawn out into filaments of exceptionally'low denier as compared with the filaments obtainable from similar solutions containing no water or comparatively small proportions ,ofwater. q According to the present invention the production of filaments of low or relatively low denier, is carried out'by subjecting to a stretch-spinning operation a solution of cellulose acetate-in acetone containing'more than 5' per cent'ofnwater and preferably in acetone containing relatively substantial proportions of water,for example in such proportions as will yield solutions of substantially reduced viscosity as compared with solutions'containing small proportions of water or nofwater. Preferably the water is present in; such proportions'as to yield cellulose acetate soluj tions of minimum viscosity or approximately so.- In "carrying the-invention into effect the solutions may, for example, :be extruded through suitable orificesinto an evaporative atmosphere and the issuing filaments drawn off and wound at such a-rate-as to, stretch and draw them down to the. required low. denier, e. g. a denier below. 3, such as 1.5to 2.5. I v The inventionis not restricted to the employment of solutionsof any particular lower limit of water content relatively to the aceto fi a this may vary; as before mentioned, but; the proportion of water employed in the solution relatively to the acetone will be in general greater than the proportion of about 4.5 to 5 parts by weight of water per 95.5 to 95 parts by weight of acetone, which proportion is usually present in the ace- 5 tone solutions of cellulose acetate ordinarily employed for spinning cellulose acetate yarns; for example the solutions may contain from about twice this proportion of water and upwards relatively to the acetone, and in particular may con tain about 10 to 12 parts of water or more relatively respectively to about 90 to 88 parts or less of acetone, it being understood as-before mentioned that the invention is not restricted to these proportions.

The water will be used in sufiiciently large pro portion to obtain a solution of the desired viscosity and preferably a solution of or approximately of the lowest viscosity. If lustrous filaments are desired the water should not be added- 0 or used in so high a proportion as to cause precipitation of the celluloseacetate under the.

spinning conditions.

It is understood that the cellulose. acetate may be dissolved in the acetone. or other solvent" or solvents already containing: the. desired propontion of water or that the-required. water content of the solutions may beprovided. for or adjusted by addition of water or further. water to previouslyprepared solutions of the cellulose. acetate in the solvent or' solvents before or after filtration of the spinning or extrusion. solutions. As stated previously filaments of denier below 3, for example 1.5-2.5, maybe produced in accordance with the invention, which however is not restricted to these examplesas'still finer fila ments for example of 1 denier or less may be produced.

Again, cellulose acetates of very high or extremely' high viscosity characteristics; which.

By' means of the invention, filaments, yarns filament denier, and products ofhigh tensile strength can be produced.

The invention is especially applicable to the W production of filaments, threads, yarns, films, and

the like from solutions of cellulose acetate in liquids containing acetone as solvent together" with the substantial proportions of water, but

instead or partly instead of acetone other sol- I vents, whether of higher or lower boiling point,

may be used in preparing thesolutions, while observing the condition of providing for or, ad'- justing the water content of the solution to the desired reduced viscosity and preferably the low- 7 W est degree of viscosity. For'example the acetone may contain a small proportion of "a solvent of higher boiling point, e. g. diacetone alcohol. The proportion of other solvent may be varied according to its boiling point. If desired, part of the acetone or other solvent or solvent mixture may be replaced by an organic diluent, for example an alcohol, e. g. ethyl alcohol. For instance acetone containing 7-15 per cent of alcohol and 10-5 per cent of water may be used.

The invention applies with particular advantage to the production of filamentayarns or or threads can be drawn out to low or very low threads by evaporative or dry spinning, but it may also be applied to their production by the so-called wet spinning or coagulation method.

Thin or relatively thin ribbons, films, or the like may also be produced in accordance with the invention, the solutions being extruded for this purpose through appropriately shaped dies and formed by evaporation, or run on to forming surfaces or otherwise suitably formed.

The invention is specially applicable to the manufacture of filaments, yarns, threads, ribbons and films or the like from cellulose acetate and particularlyacetone-soluble cellulose acetate, but. it may also be applied, in observing generally similar principles, to the manufacture of yarns, threads, filaments and films or the like from other cellulose esters, for instance cellulose formate, propionate, orbutyrate or from alkoxyalkacyl derivatives of cellulose referred to in the specification of U. S. patent application S. No. 3%,9757 filed 21st March 1929, or mixed' alkacylalkoxyacyl derivatives of cellulose. .referred to in the-specification of U. S. patent application S. No. 348,978 filed 21st March 19.29., orfrom ethers of cellulose, for instance ethyl, methyl or benzyl cellulose, or the corresponding. condensation products of cellulose and glycols or other polyhydric' alcohols, or other organic de-' rivatives of cellulose, especially acetone-soluble derivatives. 1

The invention includes not only the: process of producing filaments, threads and yarns as: herein referred to but also the filaments, yarns and threads produced, and also fabrics made of or containing the same. 11

The invention is illustrated but not limitedby the following example.

Example A primary cellulose acetate obtained by 55 acetylating cellulose with acetic anhydride in thepresence of acetic acid using sulphuric acid.- as" catalyst, is ripened until it has the desired degree of solubility in acetonecontaining water, for example in acetone, containing more;v than. 10-25 per cent of water. There is then prepared a 20- 25 per cent solution of the ripened acetate in ace-- tone containing water, the content of the latter being adjusted so that the solution has the desired relatively low, viscosity; the water content may be, for example, 10 12' per cent or more e. g. 15-20 per cent. The solution isthen spun through suitable orifices into a. heated atmosphere, the peripheral speed of the draw-off roll-. ers being adjusted so that the filaments are drawn down to the desired degree of fineness, for example until they are of 1.5-2 denier or less.- The filaments so produced may be continuouslywound, or twisted and wound, or subjected to other treatments asdesired.

What I claim and desire to secure by Letters Patent is:--

1. Process for" the production of filaments of low denier which comprises spinning and drawing down to filaments of low denier solutions of cellulose acetate in acetone containing suflicient. water to: yield solutions of substantially lower viscosity than that of solutions of the same concentration in acetone containing 5 per centof water. 1

2; Process of producing artificialfilaments" of low denier from cellulose acetate, which comprises spinning a solution of cellulose acetate in acetone containing 10 to 20 percent of water and denier below three. v

3. Process of producing artificial filaments of low denier from cellulose acetate, which comprises spinning a solution of cellulose acetate in acetone containing betweenli) and 12 per cent of water and drawing down the filaments until they are of denier below three.

4. Process for the production of filaments of low denier which comprises dry-spinning and drawing down to filaments of denier below 3, solutions of cellulose acetate in acetone containing sufiicient water to yield solutions of substantially lowerviscosity than that of solutions of the same concentration in acetone containing 5 per cent of water.

5. Process for the production of filaments of low denier which comprises dry-spinning and drawing down to filaments of low denier solu tions of cellulose acetate in sufficient water to yield solutions of substantially minimum viscosity.

6. Process of producing artificial filaments of fine denier from cellulose acetate, which comprises spinning into an evaporative atmosphere a solution of cellulose acetate in acetone containing 10 to 20 per cent of water and drawing down the filaments until'they are of denierbelow three. v

'7. Processof producing artificial filaments of acetone containing low denier from cellulose acetate, which comprises spinning into an evaporative atmosphere at solution of 1 cellulose acetate in acetone contain- 1 ing between 10 and 12 per cent of water and drawing down the filaments until they are of denier below two. Y v

8. Process for the production of filaments of low denier which comprises spinning and drawing down to filaments of low denier a solution of an organic derivative of cellulose in acetone containing sufficient water to yield solutions of substantially lower viscosity than that of solutions of the same concentration in acetone containing 5 per cent of water. l

9. Process for the production of filaments of low denier which comprises spinning and drawing down to filaments of low denier solutions of cellulose acetate in acetone containing an alcohol" and also containing sufficient water to,

three.

HENRY DREYFUS.

artificial I filaments 

